A barrel contains 75 gallons of water. A drain is opened, and the water flows out of the barrel at a rate of 0.5 gallon per minute.
Which equation represents y, the amount of water in the barrel at the end of x minutes of draining?
A. y = 75x + 0.5
B. y = 75х - 0.5
C. y= -0.5x + 75
D. у= -0.5x - 75
B. y = 75x - 0.5
Explanation: The amount of water in the barrel decreases by 0.5 gallons every minute, so the equation should reflect that the water is decreasing (subtracted) from the initial 75 gallons amount. The correct equation should be in the form of y = initial amount - rate of decrease multiplied by time.